Recently published results of a global study examining pre-term births reveal that male babies face greater risks while growing inside the womb, at birth and after birth.
The study, which was funded by the Bill & Melinda Gates Foundation, examined more than 15 million babies born prematurely worldwide. It found that boys have a 14 percent greater chance of being born prematurely than girls; preterm boys also have a higher risk of disability and death than preterm girls.
Disabilities include learning problems, blindness or deafness, and cerebral palsy. Male babies also have a greater risk of infections, birth complications including jaundice, and congenital conditions.
Of the 13 million preemies who survived past the first month of life, 4.4 percent had mild disability and 2.7 percent had moderate to severe disability.
One reason for the greater risks faced by boys is that they are known to mature a bit more slowly than girls. Even once they are born, girls tend to walk and talk ahead of boys. This faster development in girls is also seen in the womb: for male and female babies born at the same premature gestational age, girls will come out a little ahead in development than boys, thus improving the girls’ odds of survival and good health.
Research team leader Dr. Joy Lawn, a neonatologist at the London School of of Hygiene & Tropical Medicine in England, observed that another explanation for the greater likelihood of preterm birth and complications among boys is that mothers who are expecting a boy are more likely to experience placental problems, high blood pressure, and pre-eclampsia, a serious condition that also involves high blood pressure (and excess protein in the urine).
Yet another explanation for the greater incidence of problems for male babies is that mothers’ bodies sometimes mount immune attacks against the developing male fetus. This is because boys secrete proteins linked to the male Y chromosome, which the mother’s body doesn’t recognize, so, her system may make antibodies to fight off the “foreign” substances.
One bleak note for baby girls, though: the study found that premature girls were more likely to die within the first month of life in countries where girl infants receive less attention and medical care than boy infants.
The risk of disability and death was found to vary, based on where the babies were born, with more than 80 percent of preemies surviving and thriving in high-income countries. Preterm babies in low-income countries were 10 times more likely to die than those born in high-income countries.
The greatest number of problems for preterm babies was recorded among poor countries in South Asia and sub-Saharan Africa, with 2.2 million preemies dying and more than 600,000 having some degree of disability.
Results of the study were published in November, 2013 in the journal Pediatric Research.
By Marc Courtiol